Right cylinders dead at idle

[KoboldWrangler]

Hello--

Picked up this '88 1300, 109k miles. It had been sitting for about 6 years before I got it. I'm currently going through the motions of getting it road worthy again -- calipers, slave, carbs, etc and I am currently fighting the two right side carbs. 

 

Unfortunately there was gas left in the carbs, which goo'd up the lower quarter of them, but thankfully it wasnt too bad (unlike the 1200 i also picked up...). All the carbs received ~1hr ultrasonic bath individually consisting of hot water, dawn grease soap, and simple green max. Came out nice, used 100psi of air to blow out all the passage ways, replaced o rings, gaskets, diaphragms, and put them back together. There was only one pilot jet which I could not remove due to it stripping out. The rubber plugs are still snug in the jet blocks, but they are on my list of parts to change.

 

I for the life of me cannot get the bike to consistently idle on the right two cylinders. Sometimes, not often, it will idle on all 4, but more often than not, the idle will be low, and you can pull the right two side plugs and the idle wont change. I've had the carbs apart multiple times, and cannot get a different result. When I pull plugs, they will audibly be snapping, and the one time i had a spare plug hooked up, it had a scarily bright blue spark. Plugs when pulled will also be wet. 

 

I will be replacing spark plug boots tomorrow as a maintenance item, and will report if anything changes with that.

 

Is there something I am overlooking? Anything I should check?

 

Also, is there an easy way to remove / drill out the stuck pilot jet?

[KoboldWrangler]

edit: went back out to check for spark, its not a bright blue, but a meh purple orange color.

[Marcarl]

First you need to do a compression check. Throttle wide open on all cylinders.
You could also spray some WD40, or carb cleaner, or brake clean into the carbs to see if that changes anything.

get back to us.

[Chaharly]

You didn't happen to change the pilot jets while you had the carbs apart? I replaced mine with ebay ones and have been having similar issues ever since. I can get a consistent idle now, but I'm adjusting the screws out like 4 turns to achieve it. 

[KoboldWrangler]

On 10/25/2024 at 2:23 PM, Chaharly said:

You didn't happen to change the pilot jets while you had the carbs apart? I replaced mine with ebay ones and have been having similar issues ever since. I can get a consistent idle now, but I'm adjusting the screws out like 4 turns to achieve it. 

nope. i do my best to reuse old brass if i can.

 

On 10/25/2024 at 7:17 AM, Marcarl said:

First you need to do a compression check. Throttle wide open on all cylinders.
You could also spray some WD40, or carb cleaner, or brake clean into the carbs to see if that changes anything.

get back to us.

None of my compression gauges will screw in or push in due to the nature of the engine. Prolly will look at getting another gauge soon. I tried trickling gas into the carb while at idle. No change. I am starting to doubt this is a fueling issue.

 

update. replaced plugs and boots. no change. took the carbs back off, cleaned the right two carbs again, sealed any potential cracks in the intake boots, replaced boot screws, aaaaand...front right now consistently idles, but the rear right just refuses to idle. checking with a temp gun shows a 175*F+ difference between the rear right, and all the other headers. (also, one of the PO cracked both heads by using too long of screws on the front left and rear right upper intake boot bolt holes...found this out when oil started pouring out the bolt holes.) 

 

Something else I noticed -- i had to replace some of the coolant o rings on the front of the motor, and while letting the bike idle, theres what appears to be smoke coming out of the radiator. something tells me that this bike has a blown head gasket, and its game over for this motor. There is someone near me that has a supposedly good 1300 motor, and the odometer says 7232 miles, but that scares me that it might have 107232 miles -- mines the same way, saying 9000 miles, but the included logs show 109 miles.

 

While it was idling (yes, i know cv's dont run right without the air box) I was blipping the throttle, and noticed that the rear right has a weaker vacuum signal than the rest, resulting in the movement in the slide to be delayed. Yes, all diaphragms and o rings were replaced as well...

 

I recorded a short video kinda showing the late moving slide, and the smoke coming out of the rad.

 

Thoughts?

 

 

 

[Marcarl]

If you have a bad headgasket take the rad cap off and see if the coolant bubbles at all. If it does, it's a head gasket.

Another thought: when seating the carbs in their boots often times one will jump back out when seating another. Check and re-check to see that they are all seated firmly and properly.

[KoboldWrangler]

4 hours ago, Marcarl said:

If you have a bad headgasket take the rad cap off and see if the coolant bubbles at all. If it does, it's a head gasket.

Another thought: when seating the carbs in their boots often times one will jump back out when seating another. Check and re-check to see that they are all seated firmly and properly.

They are 100% seated

[KoboldWrangler]

is there a good source or person on the forum that offers carb rebuild services?

[KoboldWrangler]

Sorry for the sporadic posts. been pulling my hair out over this.

 

I think i finally solved it. The cylinder that was dead at idle had a stuck idle jet in the jet block. I had used guitar wire to ensure the jet was open, ultra sonic'd it multiple times, and used compressed air trying to get it cleared out, with no luck. I took the best fitting screwdriver I had, sharpened it and managed to get the idle free without too much damage. Looking at the jet it was indeed clear, but when i stuck everything in the cleaner, black crap started oozing out of the jet block from the idle jet hole. Guess there was something in there that evaded all my attempts to get clean.

 

I am still picking up the parts bike -- i have a bastard child '84 xvz12 that is in desperate need of parts (xvz1200 everything mounted to a 1300 frame, and is in very rough shape.) I plan on getting offroad-esque tires for it, and will be taking it on the KAT next year with my brother and the maxim he picked up. 

Edited 11 hours ago by KoboldWrangler